IL-1β and caspase-1 expression in the brains of FIV-infected animals with neurologic defects. A. IL-1β immunoreactivity was evident in feline monocyte-derived macrophages at 8 and 24 hr following FIV infection while caspase-1 expression was unaffected. B. CD4+ T cell count in blood of FIV-infected (n = 10) and uninfected animals (n = 6) at weeks 8 and 12 post-infection. C. Neuronal counts per high power field (400X) from FIV [+] animals versus FIV [-] controls at week 12 D. Immunohistochemical detection of Iba-1, IL-1β and caspase-1 in both striatum and cortex (CTX) from FIV [-] and FIV [+] animals (original magnification: Iba-1 and IL-1β X200; caspase-1 X600; Nissl stain, X100). Inset 'i’ shows an IL-1β immunoreactive microglial nodule. Insets 'ii’ and 'iii’ display IL-1β and Iba-1 co-immunolabeling. E. Detection of FIV pol RNA in the cortex and striatum of FIV [-] (n = 6) and FIV [+] animals (n = 10) at week 12. Performance of FIV [-] (n = 6) and FIV [+] (n = 10) animals in neurobehavioral tests of gait (F) and memory (G) at week 12 post-infection. “N.D.” indicates that virus was “Not Detected”.